DENVER -
We get only a few of these moments in our lifetimes, chances to marvel at athletic brilliance that transcends the ordinary and makes us appreciate their magnificence because of their once-in-a-generation appeal.

We remember them in our own special way, no matter how old or young we are, regardless of how jaded we've become by the sometimes endless stream of games that amount to little more than white noise when compared to moments like these.

The mention of their names bring to mind the enchanting flashes of magnificence they've given us, prompting the kind of hyperbole we offer here, knowing that no words or phrases can really do justice to what we're about to behold.

Ali-Frazier.

Bird-Magic.

Russell-Chamberlain.

Nicklaus-Palmer.

Leonard-Duran.

And now this latest -- and perhaps greatest -- matchup of all: Brady-Manning.

This is the 15th time that Peyton Manning and Tom Brady have faced one another, but this is by far the most dramatic setting. It comes as both men's careers have ripened from the radiance of their youth, through their athletic primes and now close to the conclusion of their Hall of Fame-caliber careers.

The 15th time is the most extraordinary one of all, because we know it might very well be the final time in circumstances like these: at the peak of their powers and with a Super Bowl berth on the line.

Manning, 37, is the NFL's presumptive Most Valuable Player, his fifth such honor, the most in league history. Brady, 36, is in position to become the first quarterback to play in six Super Bowls; only he and Denver's John Elway have played in five.

Brady-Manning began on Sept. 30, 2001, only a week after Brady took over for an injured Drew Bledsoe against the Jets. Brady faced Manning in his first start of an NFL career that would blossom into one of the greatest ever.

Brady was a skinny kid few had given much thought to when he was drafted a year earlier. Manning, the highly trumpeted No. 1 overall pick in 1998, was more than three years into a career that eventually would launch him to heights rarely seen from a quarterback.

Brady won that first matchup, 44-13, and went on to win his first of three Super Bowl championships that season. He has gotten the Patriots to two more Super Bowls, losing both to the Giants. Along the way, he has beaten Manning 10 of 14 times, most recently in a thrilling regular-season comeback at Gillette Stadium in November. He rallied the Patriots from a 24-0 halftime deficit to pull out a 34-31 overtime win.

Along the way, the two men have grown to appreciate one another.

"Tom Brady is an incredibly competitive quarterback that has played his best football in so many big games," Manning said. "I think the one thing that jumps out about Tom is just his consistency. I feel like he's been a better player each year than he was the year before, and that, to me, speaks to his work ethic in the offseason, his refusal to be complacent or satisfied."

Brady certainly appreciates Manning, but he is careful not to make this an individual matchup. For Brady, this is all about Patriots-Broncos and the right to go to the Super Bowl. Period.

"Truthfully, I'm just not focused on that [rivalry] at this point," he said. "I wake up every morning to try to come here [to practice] and focus on my job and do what I need to do. I don't read much, I don't do much. I just show up and get ready for practice and then get my treatment and go out and get ready to play and know the challenge ahead. It's just not really on my mind, not this week."

Their numbers are simply stratospheric. Manning, only two years removed from a series of four surgical procedures on his neck, set an NFL record for most touchdown passes (55) and most passing yards (5,467). Manning broke Brady's touchdown record of 50, which he set during the Patriots' 16-0 season in 2007.

Brady has been at or near the top in almost all passing categories throughout his career, although his production dipped somewhat in 2013, mostly because of a dramatic makeover at the Patriots' skill positions and tight end Rob Gronkowski's season-ending knee injury. Brady finished with 4,343 yards and 25 touchdown passes, his fewest scoring passes since his 24 in 2006.

But beyond the numbers, it's what's in their heads and hearts that sets these men apart from everyone else of their generation -- and all but a handful of legendary NFL passers.

They work at their craft with an intensity and fervor that few can duplicate. Manning scribbles his football knowledge in spiral-bound notebooks he has kept since his first season in 1998, a reference tome that might be the most advanced football information ever written. He constantly refers back to notes he has taken over the years, and has no doubt done the same in preparation for Sunday's matchup.

Brady spends nearly every waking moment during the season -- and a good chunk of the offseason -- locked in on football with a laser-like focus. He's a gym rat who never can get enough information and put in enough time. And he never wants it to end.

I asked him a little more than a year ago if he'd ever contemplated retirement, and he gave me a funny look as we walked back to the Patriots' locker room after a practice during training camp. He shook his head no and said, "I don't know what the hell else I'd do."

Brady lives for moments like this, and now it's here again: a chance to play for the championship and a chance to go up against the only man who can approach his accomplishments.

Brady-Manning, Part 15. The moment is almost here. It is what these men live for. It is what we get to cherish, especially knowing that this might be the last time.

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